The invention relates to a fastener. The invention is specifically related to a self-attaching double or single ended stud.
Studs are used by the automotive industry to assemble vehicles in which many components of various kinds are attached to metal plates or panels. For example studs are used to attach lamps, brackets, modules, and sheet metal parts to the vehicle. When such parts are attached a nut is placed over the end of the installed stud and the nut is tightened with rotating tools such as an air or electric torque gun, set to the specified torque values. The self-attaching stud must therefore have the necessary and sufficient anti-torque or rotation resistance (the force that keeps the stud from rotating on the mating metal plate when the nut is tightened on the stud).
When self-attaching studs are being driven into a metal panel the studs may be continuously supplied to the installation tooling through an outlet of a supply device, such as a hopper. Studs are easily adapted to automatic feeding machines because of the large length to diameter ratio. The larger the ratio the more efficient the high-speed feeding operations become.
After a component is attached to the stud on the metal plate, external forces such as vibration and shear and tensile forces are applied to the joint (the stud and nut combination with the attached part). These forces act upon the stud from the pull through direction attempting to pull the studs from the metal plate in which they are attached. Therefore, the installed stud must have sufficient push out and pull out resistance. Previously, the only way to ensure a very high push out or pull out force was to weld the stud to the mating material. Earlier attempts to use double-ended studs that were not welded resulted in studs with very low push-in and push-out values. A low push-out value limits the number of applications in which the stud can be used, since a stud with a low push-out value can not attach parts of any significant amount of mass.
Thus, there is a need in the industry for a stud that can be attached by means other than welding where the stud also has a very high push-out force, and where the stud can be configured as either a single-ended stud or a double-ended stud.
One aspect of the present invention is a stud for installation in a host panel and for fastening a component to the host panel, which includes at least one shaft, having a longitudinal axis. An annular flange extends radially from the shaft at a substantially right angle with respect to the longitudinal axis. A shoulder for engagement with the host panel has a top adjacent to the shaft and a base adjacent to the flange. The shoulder extends radially from the shaft wherein the shoulder and the flange define an undercut therebetween at the base of the shoulder such that a diameter of the shoulder is smaller at the base than at the top. At least one anti-rotation tab is located intermediate between the shoulder top and the flange, and is aligned for engagement with the host panel.
Another aspect of the present invention is a double-ended stud for installation in a host panel and for fastening a component to the host panel wherein the double-ended stud includes a shaft having a longitudinal axis and a first and a second end. An annular flange coaxial to the shaft is positioned intermediate between the first and second ends of the shaft. A shoulder is positioned adjacent to a surface of the flange and is coaxial thereto wherein the shoulder has an outer peripheral face. The peripheral shoulder face and the flange surface define an acute angle therebetween. At least one anti-rotation tab extends from one of either the flange surface or the shoulder""s outer peripheral face.
Yet another aspect of the present invention is a method for installing a double-ended stud in a host panel aperture wherein the stud has an annular flange with anti-rotation tabs and further includes a shoulder with a crown and a face with a back angled portion. The method for installation comprises the steps of supporting one end of the stud and the stud flange with an installation fixture and then placing an installation punch over the opposite end of the stud wherein the installation punch has a face portion bearing on the shoulder crown and an annular protrusion bearing on the panel area proximate to the panel aperture receiving the stud. Next, a force is applied by the punch in a direction toward the installation fixture and deforming the panel material around the anti-rotation tabs. The applying force further causing the flowing of panel material that defines the panel aperture into the back angled portion of the shoulder and deflecting the shoulder crown radially outward to engage the panel at the periphery of the panel aperture.
These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings.